The medium-entropy alloy CrCoNi is known for its exceptional high fracture toughness. In contrast, the crack propagation behavior in the near-threshold regime was rarely examined in the past. However, this region is quite interesting as the microstructure has a significant impact on the threshold against fatigue crack propagation. Therefore, the present study focuses on how to tailor the microstructure using Equal-Channel Angular Pressing (ECAP) (channel angle of 120°) and subsequent heat treatment. Five different microstructures are investigated: a recrystallized initial state, one after three ECAP passes as well as after three ECAP passes and several heat treatments to obtain different degrees of recrystallization. Interestingly, the fatigue threshold is not significantly influenced by the induced degree of deformation and the subsequent heat treatment. However, the crack growth rate strongly fluctuates for microstructures resulting from ECAP processing and heat treatment. To examine the crack path near the crack tip and in the Paris region, electron backscatter diffraction (EBSD) is used. EBSD shows that the crack fracture mode is transgranular for all conditions. In addition, annealing twins change the crack path, resulting in a tortious crack path in the near-threshold region. Furthermore, the crack tip and the crack in the Paris region are additionally examined by EBSD at a depth of 50 µm below the last observation plane. This allows for an enhanced 3D understanding of the crack propagation behavior in different microstructures.